Most methods simply seek to reconstruct SR images with high PSNR and SSIM. However, the improvement in reconstruction accuracy is not always accompanied by an improvement in visual quality. Blau et al. [1]} pointed out that there was a perception-distortion trade-off. It is only possible to improve either perceptual quality or distortion, while improving one must be at the expense of the other. Hence, in this section, we provide methods to ease this trade-off problem, hoping to provide less distortion while maintaining good perceptual quality of the image.
